The current method of measuring the depth of penetration of a drilling tool into the ground during well drilling is to measure the length of each drill pipe in the drill string. As well the depth at which casing is placed and cemented in the ground is deduced by measuring each individual casing joint. The various tubulars in a string will have variable lengths, which means that a simple count of the tubulars will not work to determine the total length. Each tubular must be measured. Normally, this is done by using a tape measure. One rig hand holds one end of the tape measure at the box end of the tubular or casing joint, while the other rig hand holds the other end of the tape measure at the pin end of the tubular. The rig hands then read off the measurement and write it down. This data is then physically entered into a computer system. This method is archaic and prone to errors.